Mechanistic Insight Into Electrocatalytic Nitrogen Reduction to Ammonia Over PdBi Single-Atom Alloys

Electrocatalytic nitrogen reduction is promising for sustainable ammonia production, but is hindered by a high protonation energy barrier and severe competition from the hydrogen evolution reaction. Although PdBi single-atom alloy has been demonstrated to be an efficient electrocatalyst for electrochemical nitrate reduction to ammonia, the underlying mechanism of the electrocatalytic nitrogen reduction reaction over this type of catalyst remains unclear. Herein, a PdBi single-atom alloy is prepared by anchoring Bi single atoms onto thin Pd nanosheets and applied for the electrocatalytic nitrogen reduction reaction. The induced electronic coupling between Bi and Pd atoms optimizes charge distribution, thereby enhancing N₂ adsorption-activation and decreasing the free-energy barrier of the rate-determining step of *N₂ → *NNH from 0.71 to 0.61 eV. The optimized PdBi₁₀ single-atom alloy exhibits superior electrocatalytic activity toward the electrocatalytic nitrogen reduction reaction, delivering an ammonia yield of 46.9 µg h^-1 mg^-1 with a Faradaic efficiency of 13.3% at -0.2 V (vs. RHE), along with excellent long-term stability. This work provides mechanistic insights and design principles of engineering single-atom alloy electrocatalysts for efficient and durable electrocatalytic nitrogen reduction reaction to ammonia.